Civil Engineering - Strength of Materials - Discussion

I agree @ Subham,

Because they given 'e' in kg/cm^2, So only we have to convert length in cm, after calculation we get the answer in cm, then multiplied by "10" that gives the answer in mm.

So finally option "A" right answer.

C is the correct answer.

Right answer is 0.02274mm.

@All.

A) If we convert all the necessary data into "mm" & keeping load in "kgs",
We get,
(3000*5000)/(314.16*2.1e^6) = 0.0227 mm.

B) If we covert the data in "cm", we get
(3000*500)/(3.142*2.1e^6) = 0.2273 cm.

C) If we convert only length in "mm" & keeping dia in "cm" we get,
(3000*5000)/3.142*2.1e^6) = 2.274 unknown units and wrong procedure.

D) If we convert load in "N" & all dimensions in "cm", we get
(3000*9.81*500)/(3.142*2.1e^6) = 2.230 cm.

E) If "E" is given in Kgs/cm^2, we get
(3000*5000)/(314.16*2.1e^8) = 0.0002274 mm, which is not in the given answer.

But the given answer is in "mm", and the correct one is "C" which is in "mm"

Units of E is in kg/cm2. So the answer is A.

Given;

dl = (PxL)/(A.xE)
P = 3000kg, L=5m = 500cm.
A = 3.14x (2/2)>^2 = 3.14 cm^2.
E = 2.1x10^6 it/cm^2.

Putting the values in the formula.
dl = (3000kg x 500cm)/(3.14cm^2x2.1x10^6kg/cm^2).

Deduct the dimensions and zero we get;
dl= (15/3.14x2.1x10)=15/65.94=0.2275mm.
So, Answer :B

A = 314.16,
P=3000kg=3000*10=30000N,
L=5m=5000mm,
E=2.1*10^6.

Elongation= Pl/AE.
= (30000* 5000)/(314.16 * 2.1 * 10^6).
= 0.2275 mm.
So, B is the right answer.

0.02275 is the right answer.

C is the correct answer.

P = 3000kg = 30000N,
L = 5000mm,
D = 20mm,
E = 2.1*10^6 N/mm^2.
So elongation = 30000*5000*4/3.14*400*2.1*10^6,
Ans = .2274... = 0.2275.